Magnetic remote control switch



Aug. 12, 1969 E. w. BOLLMEIERI 3,461,354

MAGNETIC REMOTE CONTROL SWITCH Filed May 27, 1966 I N V E TOR. f/n/z. /4, 4YNE504 AME/5? 3,461,354 MAGNETIC REMGTE (IONTROL SWITCH Emil Wayne Bollmeier, St. Paul, Minn, assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn, a corporation of Delaware Filed May 27, 1966, Ser. No. 553,561 Int. Cl. 1101b 47/02, 51/30 U.S. Cl. 317-156 8 Claims ABSTRACT 01'' THE DISCLOSURE A magnetic control for remotely operating a switch includes a ferromagnetic core having two closed legs completing a closed magnetic circuit and a third open leg parallel to the two closed legs and wherein two opposed core faces define a narrow gap; an armature in position of optionally contacting either core face, which armature by its movement operates a switch; a magnetic fiux source positioned to establish a unidirectional flow of flux across the armature and one of the core faces which the armature contacts; and primary and secondary coils around the two closed legs, the secondary coil being connected to a switch and a rectifier for shorting the secondary coil to allow unidirectional current flow in a desired direction in the secondary coil. The secondary coil current, depending upon its direction alters the flux flow in the core and thereby changes the relative magnetic attraction of the core faces for the armature.

This invention relates to electric switch or relay devices. An important practical embodiment is a relay for remote control of house lighting circuits and wherein the voltage at the switch is much lower than the line voltage.

Prior to the present invention, control of lighting circuits by low voltage switching has necessitated the presence of a separate transformer or other means for reducing line voltage to desired signal voltage, together with a latching relay or equivalent electronic circuitry or other means for making or breaking the lighting circuit when actuated by low voltage signal. The present invention combines the functions of transformer and relay in novel manner and provides a unitary relay device of reduced complexity and size and of improved operating characteristics.

The invention provides an electrical switching relay device comprising a core including first and second legs completing a closed magnetic circuit and an open leg which is functionally parallel to the second leg, an armature in position for contacting either of the opposed faces of the open leg, means for establishing a flow of flux across the armature and the contacted core face, load switch means operated by the armature, a primary coil around the first core leg, and a secondary or switching coil around the second core leg, together with auxiliary or optional control components all as will now be further described and identified in connection with the appended drawing, in which:

FIGURE 1 is a schematic representation of a presently preferred switching device shown connected to a source of electric power and to a load, and

FIGURE 2 represents a modified form of switching device.

The device of FIGURE 1 comprises a high magnetic permeability, low loss ferromagnetic core 10 having a first leg 11 and a second leg 12 forming parts of a closed magnetic circuit, and an open leg 13, the opening being defined by faces 14 and 15. A primary coil 16 around the first leg 11 is connected directly to the power supply lines 17. A secondary coil 18 around the second leg 12 is connected to a switch 19. A permanent magnet 20 ex- "116d States Patent F 3,451,354 Patented Aug. 12, 1969 tends from one branch of the open leg 13 to a post 21 having high magnetic permeability and against which is pivoted an armature 22. The other end of the armature lies between the core faces 14 and 15 and may be placed in contact with either of them. The mass of the armature must be sufficiently small to permit rapid operation under the forces supplied. The armature 22 is lightly contacted by an insulating peg 25 carried by a flexible contact arm 23 which further carries a contact point 24 and is itself supported on the post 21 being insulated therefrom by an intervening insulating spacer. The supported end of the arm 23 extends as terminal 26. A second contact point 28 is supported on a rigid arm 29 in position for making connection with contact point 24 when the armature 22 is in contact with the upper core face 14. Arm 29 ends in terminal 30, and is insulated from arm 23 and from post 21 by suitable intervening strip insulation.

Switch 19 is in the form of a momentary-contact double pole double throw switch and includes a diode 31 or other means for rectifying the alternating current induced in coil 18 when the switch is in closed position.

Optionally, an overload coil 32 is incorporated around one branch of open leg 13 and forms a part of the load circuit. A similarly positioned coil may alternatively or additionally be included for connection into a master circuit as an over-ride coil, to permit independent control of the armature position from an external D.C. source.

The operation of the device is as follows. Power supplied to the primary coil 16 induces magnetic flux in the core 10. The majority of the induced flux flows within the closed magnetic circuit, i.e. through legs 11 and 12. The armature 22 is held in the position indicated in FIG- URE 1, i.e. in partial contact with core face 15, by the magnetic flux provided by the permanent magnet 20 and contained within the closed magnetic circuit completed through post 21, armature 22, and the portion of the core leg 13. Momentary closing of switch 19 in the proper direction completes the electrical circuit through coil 18 in that direction of flow of the induced current which establishes across the gap in open leg 13 a magnetic flux impulse of sufficient intensity and in the proper direction to overcome the holding action of magnet 20 across the partial gap between the armature and lower core face 15 and to flip the armature into partial contact with the opposed upper face 14. This movement of the armature brings together the contact points 24, 28 to permit current to flow through the load L. The armature is retained in the new position by magnetic fiux from the magnet 20 in the closed circuit now completed through post 21, armature 22, and the connecting portion of core 10 inand 28 separated.

Reversing the switch 19 reverses the direction of flux set up by the secondary coil 18 and drives the armature to the original position, i.e. with the contact points 24 and 28 separated.

The overload coil 32, where present, carries the full load for which the load circuit is designed. Under any excessive overload, however, the flux imparted by coil 32 is sulficient to cause the armature to be displaced from contact with face 14 and into contact with face 15, thereby opening the load circuit.

It will be appreciated that momentary closing of switch 19 in the proper direction is sufficient to reverse the position of the armature, so that a push-button type of switch is adequate for such control purposes.

In the modification illustrated in FIGURE 2 a coil 40 around an extension of the core 41, together with a diode 49 and a capacitor 50, takes the place of the permanent magnet 20 of FIGURE 1. A leaf spring 45 attached to post 43 supports the armature 42 and is adjusted to bias it lightly against pole face 44 so as to open the contacts 46, 51 in the event of power failure. If necessary, the pole face 44 may be partially shorted with a copper D-ring or the like, not shown, for the purpose of providing a more effective magnetic holding effect. Fixed contact point 46 makes contact with point 51 carried by the armature 42 when the latter is in contact with the pole face 48, to complete the circuit through the load L.

An illustrative example in the form of a switch or relay for operating a house lighting circuit on a 120 volt AC power source and by remote control at low voltage may have the following dimensions with reference particularly to the structure indicated in FIGURE 1. The core is built up of laminations of fiat soft iron sheets to a crosssectional dimension, in each of the several branches, of A X A inch. Coil 16 contains 4000 turns of No. 40 copper magnet wire; coil 18 contains 2000 turns of No. 36 wire; and oveload coil 32 contains 10 turns of No. 14 wire. The gap between pole faces 14 and is $4 inch. A strip of phosphor bronze 10 mils in thickness and 4 inch in width forms the contact arm 23. The armature 22 consists of a strip of soft iron x A x 1% inch in dimensions, one end being knife-edged to serve as a fulcrum. The permanent magnet is an Alnico V high coercivity bar magnet having the dimension A x /2 X 1 inch. The diode 31 is a 100 volt, ampere, general purpose diode.

What is claimed is as follows:

1. An electrical relay switching device comprising:

a ferromagnetic core including first and second legs completing a closed magnetic circuit and a third open leg parallel to said second leg and wherein two opposed core faces define a narrow gap;

an armature in position for optionally contacting either of said opposed core faces;

a source of magnetic flux in position for establishing a undirectional flow of magnetic flux across said armature and the one of said faces with which said armature is in contact;

switch means for connection to a load circuit and actuated by said armature in flipping from one to the other of said faces;

a primary coil around said first leg for connection to a source of AC electric power; and

a secondary coil around said second leg for connection across rectifying switch means for providing a flow of unidirectional current in the secondary coil and for selecting the direction of current fioW.

2. The device of claim 1 wherein the said source ofmagnetic flux comprises a coil around a core leg common to both of the closed flux paths across the armature and the said faces.

3. The device of claim 1 wherein the said source of magnetic flux comprises a permanent magnet forming a core leg common to both of the closed flux paths across the armature and the said faces.

4. The device of claim 1 including switch means for momentarily connecting across said secondary coil and comprising an AC rectifier.

5. The device of claim 1 further comprising:

an overload coil around a branch of said third open leg for connection into the load circuit.

6. The device of claim 1 further comprising:

an override coil around a branch of the third open leg for external connection.

7. The device of claim 4 further comprising: an overload coil around a branch of said third open leg for connection into the load circuit.

8. The device of claim 4 further comprising: an override coil around a branch of the third open leg for external connection.

References Cited UNITED STATES PATENTS 3,153,178 10/1964 Martin 335-234 2,860,263 11/1958 Sparrow 335--243 X LEE T. HIX, Primary Examiner US. Cl. X.R. 33599, 234, 243 

